Carbohydrate determinants play important roles in cellular differentiation and migration via cell-cell interactions. A common carbohydrate precursor may be either fucosylated by a-1,3-fucosyltransferase (FucT) to yield the CD15 epitope (the topic of this project) or acted upon by (the subject of Project I). It is hypothesized that a comparison of their expression patterns in different cell types may lead to an understanding of the mechanisms that regulate their expression. Based on studies during the current funding period of epitope expression patterns it is proposed that CD15 may play a role in both granule neuron migration and Purkinje cell maturation. Future studies (Specific Aim 1) will characterize the cell- specific expression of alpha-1,3 glucosyltransferase in rodent cerebellum dia double label in situ will determine the effect of over-expression of defined glycotransferases via viral vectors in cerebellar cells on CD15 and related epitope expression. Specific Aim 3 will assess the functional consequence of perturbing CD15 and SGC epitope expression during cerebellar development by assessing cell migration and dendritic growth. It is anticipated that these experiments will provide information on the role of CD15 in postnatal cerebellar development.